Trip-free circuit breaker with manually operated contact deflecting means



March 2, 1965 H. J. HAMMERLY TRIP-FREE CIRCUIT BREAKER WITH MANUALLY OPERATED CONTACT DEFLECTING MEANS Filed Nov. 7, 1962 All //v VE/VTOR. HERMAN J HHMMERLY,

M C By R ATTORNEY United States Patent 3,171,919 TRIP-FREE CIRCUIT BREAKER WITH MANUALLY OPERATED CONTACT DEFLECTING MEANS Herman J. Hammer-1y, Plainville, Comm, assignor to General Electric Company, a corporation of New York Filed Nov. 7, 1962, Ser. No. 236,165 3 Claims. (Cl. 200-88) My invention relates to electric circuit breakers and particularly to electric circuit breakers of the type suited for control of small branch lighting and power circuits such as commonly used in residential buildings.

Electric circuit breakers of the type used in such residential applications are required to meet a number of tests as specified by electrical inspection authorities, including the Underwriters Laboratories.

These include tests such as the following:

(1) Calibration: breaker must trip, i.e., open automatically, on the occurrence of predetermined current conditions, within a predetermined time.

(2) Overload interruption: breaker must interrupt a given excess current, such as six times normal current, a given number of times, such as 50 times, without damage to the breaker.

(3) Heat rise: breaker temperature at terminals, must not rise beyond a predetermined limit under current-carrying conditions.

(4) Endurance: breaker must successfully interrupt its rated current a given number of times, such as 6000 times, and must further operate without load a given number of additional times, such as 5000 times.

(5) Short-circuitt breaker must successfully interrupt a short-circuit current on a system having 5000 amperes available, at least three times without destroying itself.

(6) Dielectric: after all of the above tests have successfully been passed, breaker must be able to withstand a voltage of over 1000 volts without breakdown due to such causes as surface carbonization, condensed metal vapor, etc.

The combination of these various requirements have been met heretofore by relatively complicated circuit breaker mechanisms, usually involving over-center type operating springs and costly latching arrangements.

It is an object of the present invention to provide a residential type circuit breaker which is capable of meeting the requirements of electrical inspection authorities and of the Underwriters Laboratories which does not require a complicated operating mechanism.

It is another object of the invention to provide a residential type circuit breaker which has a minimum number of operating parts and is easy to assemble.

It is a further object of the invention to provide a residential type circuit breaker which is capable of responding quickly to current overloads of a predetermined magnitude by magnetic action.

In accordance with the invention in one form, an electric circuit breaker is provided including an insulating casing. An elongated insulating slide is supported in the casing and carries a bridging contact member. A pair of relatively stationary contacts are provided on either side of the insulating slide and are adapted to be interconnected by the movable bridging contact member in one position of the insulating slide. An operating handle is provided for resetting the slide after tripping operation, the handle having an interengagement with one of the aforesaid stationary contact members to move it to a non-contacting position during the resetting operation, whereby to provide the equivalent of a trip free operation.

The invention will be more fully understood from the 3,171,919 Patented Mar. 2, 1965 following detailed description, and its scope will be pointed out in the appended claims.

In the drawing,

FIGURE 1 is a plan view of an electric circuit breaker incorporating the invention, one side cover of the insulating casing being removed;

FIGURE 2 is a partial plan View similar to FIGURE 1, showing the parts in a different operated position.

FIGURE 3 is a perspective view of the circuit breaker of FIGURE 1, the cover being shown in place, and

FIGURE 4 is a fragmentary sectional View, taken generally on the line 4-4 of FIGURE 1.

In the drawing, the invention is shown as incorporated in an insulating casing comprising a generally rectangular base or body 10 having a back wall 11 and peripheral upstanding walls including opposed side walls 12 and 13, and top and bottom walls 14 and 15. The body 10 is adapted to have its open side wall closed by a generally planar insulating cover 16, attached to the body 10 by suitable means, such as by rivets 17.

A first terminal member 18, formed of flap strip metal is retained in the base 10 by being received in a corresponding slot 19 therein. The strip 18 has a notch 20 cut therein (see FIGURE 4) and the base 10 is provided with a corresponding projection adapted to be received in the notch 20 for the purpose of holding the strip 18 in place.

A magnetic field piece 21 is also provided, which is generally U-shaped and has its bight portion extended as at 22 to carry a calibrating screw 23, to be described. A flexible conductor 25 is connected at one end to the terminal 18, extends upwardly between the side walls 24 of the field piece 21, and downwardly outside one of the side walls 24 and is connected to the lower end of a bimetallic strip 26. The bimetallic strip 26 is rigidly fastened by suitable means, such as by welding, to a stationary contact support member 27. The stationary contact support member 2'7 is rigidly mounted in the casing 10 by being received within a closely conforming generally L-shaped recess 28. The contact supporting member 27 carries a stationary contact 29 adjacent its outer end.

A second, resiliently mounted, stationary contact 30 is suported on a generally L-shaped extension 31 of a resilient contact support arm 32 which forms an integral extension of a terminal 33. The contacts 29 and 30 are adapted to be bridged or interconnected by a generally circular or disc-shaped bridging contact member 34 carried in an opening in an insulating slide member 35. The insulating slide member 35 has its opposite edge portions slidably guided in grooves in the back wall 11 of the casing 10 and in the inner side wall of the cover 16. The slide 35 includes an integral offset portion 36 providing a recess receiving a compression spring 37 which abuts against the lower wall 15 of the casing 10. The upper end of the insulating slide 35 includes an enlarged portion 38 and a generally cylindrical boss 38A which serves to retain the one end of a handle compression spring 3?,

the other end of which engages a manually engageable handle member 40.

The handle member 40 includes an elongated inwardly directed extension 41 having a cam surface 42 engageable with an outwardly directed end portion 32A of the contact support member 32, for a purpose to be described.

A combination armature-latch member 44 is pivotally supported at 45 in corresponding recesses in the back wall 11 of the casing 10 and the inner surface of the cover 16. The armature-latch member 44 is biased clockwise as viewed by spring member 46, and includes a latch or ledge portion 47 adapted to engage a latch projection 48 integral with the insulating slide 35. The armature-latch member 44 also includes a bent-over end portion 49 having a laterally extending arm, not shown, extending behind the lower end of the bimetallic strip 26, so that when the lower end of the bimetallic strip 26 moves to the right as viewed in FIGURE 1, the armature-latch member 44 is carried with it.

'The operation of the circuit breaker will be understood by reference to FIGURES 1 and 2. In FIGURE 1, the parts are shown in the condition which they occupy when the circuit breaker is on. In this position, the contact bridging member .34 extends between the stationary contact 29 and the contact 30. The contact 30 is resiliently biased into engagement with the contact 34- by reason of the inherent bias of the contact supporting strip 32. The bridging contact member 34 is preferably free-floating, so that the pressure applied thereto by the contact 30 also acts between the contact 34 and the contact 29. The circuit in this condition, is therefore complete from the terminal 18, through the flexible conductor 25 which makes one complete turn about the magnetic field piece 21, to the bimetallic strip 26 (Which also passes through the field piece 21) to the contact support member 27, to the stationary contact 29, to the bridging contact 34, to the stationary contact 30, to the stationary contact support 32, to the outgoing terminal 3043. The compression spring 37 acts on the offset 36 of the slide 35, urging the slide upwardly as viewed. Movement of the slide 35 in this direction, however, is prevented by engagement of the latch projection 43 with the latching surface of the armature-latch member 44.

On the occurrence of predetermined over-current conditions, the bimetallic strip 26 warps so as to cause the lower end thereof to move to the right as viewed in FIG- URE 1. Such movement causes the lower end of the bimetallic strip 26 to engage the armature-latch extension 49, moving the armature-latch member to a position where the latch projection 48 of the insulating slide 35 is released from the latch surface 47. This permits the compression spring 37 to move the insulating slide 35, together with the bridging contact 34, upwardly, interrupting the circuit between the terminals 18 and 33.

Upon the occurrence of a sudden high overload, the magnetic field piece 21 becomes energized sufficiently to attract the armature-latch member 45 to it, also moving the latch surface 47 away from the latch projection 48 and permitting tripping in a manner similar to that described above.

Following tripping, the circuit breaker may be reset and reclosed by pressing inwardly on the operating handle 40. This moves the handle inwardly until the abutment 40A of the handle engages the abutment 38A of the slide 35 and moves the slide 35 downwardly toward relatched position. Before the movable contact 34 reaches a position in which it once again bridges the stationary contacts 29 and 30, the cam surface 42 of the extension 41 of the handle ill engages the end portion 32A of the contact support 32, and moves it to the left as viewed, thereby moving the contact 30 to a position in which it cannot be engaged by the bridging contact member 34 when returned to its initial position.

After the insulating slide 35 is relatched on the armature-latch member 44, the handle dit is released, and returned to its upper position by the compression spring 38. When this occurs, the cam surface 42 is moved away from the end 32A of the support strip 32, permitting the strip 32 to move the stationary contact 30 into engagement with the bridging contact member 34-, thereby completing the circuit.

It will be observed that this action provides a trip free function, since it is not possible to hold the contacts closed by holding the handle in any predetermined position. Thus if the handle is held in its inward position as described above, the cam surface 42 engages the end 32A of the support strip 32 and retains the contact 30 in an open circuit position, as shown in FIGURE 2.

For the purpose of providing ambient temperature compensation action, the calibrating screw 23 is preferably made of a high expansion material, such as a nickel alloy or nylon. It will be observed that an increase of temperature of the circumambient atmosphere, will cause the bimetallic strip 26 to assume an arcuate condition so as to move the lower end toward the right as viewed, to tend to cause tripping in the same way that heating of the bimetallic strip due to current passing therethrough would operate. Such ambient temperature increase, however, would also increase temperature of the calibrating screw 23, thereby increasing its length. This causes the calibrating screw to act on the bimetallic strip near its mounting to deflect the lower end of the strip toward the left as viewed, thereby offsetting or compensating for the action of the increased ambient temperature on the bimetallic strip.

While the invention has been disclosed in only one particular embodiment, it will be readily apparent that many modifications thereof may readily be made. It is intended, therefore, by the appended claims, to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to' secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising:

(a) a casing of insulating material,

(b) an elongated slide of insulating material slidably supported in said insulating casing,

(e) a bridging movable contact member carried by said insulating slide adjacent one end thereof,

(d) resilient biasing means biasing said insulating slide for longitudinal movement in a first direction,

(a) an elongated resilient contact strip extending parallel to and spaced away from said insulating slide at one side thereof, said strip having one end thereof fixedly mounted in said insulating casing, and having its other end laterally and resiliently movable,

(f) a first relatively stationary contact carried by said resiliently movable end of said contact strip, in juxtaposition to said bridging contact,

(g) a second relatively stationary contact fixedly mounted in said insulating casing at the opposite side of said bridging contact from said first stationary contact,

(11) an elongated bimetallic strip extending parallel to and spaced away from said insulating slide at the side thereof opposite said contact strip, said bimetallic strip having one end thereof fixedly mounted in said casing adjacent said second stationary contact and electrically connected thereto, the other end of said bimetallic strip being laterally movable in response to heating of said strip by electric current passing therethrough,

(i) latch means releasably holding said insulating slide in latched position against movement in said first direction due to said biasing means,

(j) means connecting said other end of said bimetallic strip to said latch means to cause releasing movement of said latch means upon predetermined movement of said end of said bimetallic strip,

(k) a push-type manually operable handle member supported in said casing for reciprocal rectilinear movement between outer and inner actuated positions,

(1) said insulating slide being movable between a latched position in which said bridging contact is between said stationary contacts and a released position in which said stationary contact is longitudinally displaced from between said stationary contacts, said handle being engageable with said insulating slide to move said slide from said released to said latched position when said handle is moved from said outer to said inner position, and

(m) means carried by said handle and engageable with said other end of said contact carrying strip to move said contact carrying strip laterally away from said slide, whereby to move said first relatively stationary contact to a. position in which it is out of engagement with said bridging contact member when said slide is moved to said latched position by said handle.

2. An electric circuit breaker as set forth in claim 1 wherein said latch means comprises a magnetic armature, a generally U-shaped magnetic field piece surrounding said bimetallic strip and having its bight portion on the opposite side thereof from said armature portion whereby said bimetallic strip serves to energize said magnetic field piece.

3. An electric circuit breaker comprising:

(a) a casing of insulating material,

(b) a pair of electrical contacts mounted in said insulating casing in opposed spaced apart relation therein,

(0) an elongated slide of insulating material slidably supported in said insulating casing and movable between open and closed circuit positions respectively,

(d) resilient biasing means in said insulating casing biasing said insulating slide toward said open circuit position when said slide is in said closed circuit position,

(e) current responsive latching means in said insulating casing releasably retaining said insulating slide in said closed circuit position,

(f) said contacts being electrically interconnected when said insulating slide is in said closed circuit position and said contacts being electrically separated by a portion of said insulating slide when said slide is in said open circuit position,

(g) an elongated resilient contact strip extending parallel to and spaced from said insulating slide at one side thereof, said strip having one end thereof fixedly mounted in said insulating casing and having its other end laterally movable,

(h) a first one of said contacts being carried by said laterally movable end of said contact strip,

(i) an elongated bimetallic strip extending parallel to and spaced away from said insulating slide at the side thereof opposite from said contact strip, said bimetallic strip having one end thereof fixedly mounted in said casing adjacent the second one of said contacts and electrically connected thereto, the other end of said bimetallic strip being laterally movable in response to heating of said bimetallic strip in response to electric current,

(j) latch means releasably holding said insulating slide in latched position against movement in said first direction due to said biasing means,

(k) means connecting said other end of said bimetallic strip to said latch means to cause releasing movement of said latch means u-pon predetermined movement of said end or" said bimetallic strip,

(Z) a reciprocably operable manual operating handle member supported in said casing and movable between first and second actuated positions, for moving said insulating slide from said open circuit to said closed circuit position, and

(m) means carried by said handle and engageable with said other end of said contact carrying strip to move said contact carrying strip laterally away from said slide to an open-circuit position as said handle moves said slide to said latched position.

References Cited by the Examiner UNITED STATES PATENTS 1,704,379 3/29 Aichele 200-116 1,909,174 5/33 Grady 20088 X 2,024,216 12/35 Grady 200-406 2,027,238 1/3 6 Lindstrom 20088 2,052,564 9/36 Grady 20088 2,156,761 5/39 Jackson et a1 200-116 2,191,501 2/40 Schmidt 2001l6 2,474,762 6/49 Sundt 2001 16 2,842,641 7/58 Page 200116 X 3,007,018 10/61 Wood 200-116 FOREIGN PATENTS 1,072,718 1/60 Germany.

BERNARD A. GILHEANY, Primary Examiner. 

3. AN ELECTRIC CIRCUIT BREAKING COMPRISING: (A) A CASING OF INSULATING MATERIAL, (B) A PAIR OF ELECTRICAL CONTACTS MOUNTED IN SAID INSULATING CASING IN OPPOSED SPACED APART RELATION THEREIN, (C) AN ELONGATED SLIDE OF INSULATING MATERIAL SLIDABLY SUPPORTED IN SAID INSULATING CASING AND MOVABLE BETWEEN OPEN AND CLOSED CIRCUIT POSITIONS RESPECTIVELY, (D) RESILIENT BIASING MEANS IN SAID INSULATING CASING BIASING SAID INSULATING SLIDE TOWARD SAID OPEN CIRCUIT POSITION WHEN SAID SLIDE IS IN SAID CLOSED CIRCUIT POSITION, (E) CURRENT RESPONSIVE LATCHING MEANS IN SAID INSULATING CASING RELEASABLY RETAINING SAID INSULATING SLIDE IN SAID CLOSED CIRCUIT POSITION, (F) SAID CONTACTS BEING ELECTRICALLY INTERCONNECTED WHEN SAID INSULATING SLIDE IS IN SAID CLOSED CIRCUIT POSITION AND SAID CONTACTS BEING ELECTRICALLY SEPARATED BY A PORTION OF SAID INSULATING SLIDE WHEN SAID SLIDE IS IN SAID OPEN CIRCUIT POSITION, (G) AN ELONGATED RESILIENT CONTACT STRIP EXTENDING PARALLEL TO AND SPACED FROM SAID INSULATING SLIDE AT ONE SIDE THEREOF, SAID STRIP HAVING ONE END THEREOF FIXEDLY MOUNTED IN SAID INSULATING CASING AND HAVING ITS OTHER END LATERALLY MOVABLE, (H) A FIRST ONE OF SAID CONTACTS BEING CARRIED BY SAID LATERALLY MOVABLE END OF SAID CONTACT STRIP, (I) A FIRST ONE OF SAID CONTACTS BEING CARRIED BY SAID AND SPACED AWAY FROM SAID INSULATING SLIDE AT THE SIDE THEREOF OPPOSITE FROM SAID CONTACT STRIP, SAID BIMETALLIC STRIP HAVING ONE END THEREOF FIXEDLY MOUNTED IN SAID CASING ADJACENT THE SECOND ONE OF SAID CONTACTS AND ELECTRICALLY CONNECTED THERETO, THE OTHER END OF SAID BIMETALLIC STRIP BEING LATERALLY MOVABLE IN RESPONSE TO HEATING OF SAID BIMETALLIC STRIP IN RESPONSE TO ELECTRIC CURRENT, (J) LATCH MEANS RELEASABLY HOLDING SAID INSULATING SLIDE IN LATCHED POSITION AGAINST MOVEMENT IN SAID FIRST DIRECTION DUE TO SAID BIASING MEANS, (K) MEANS CONNECTING SAID OTHER END OF SAID BIMETALLIC STRIP TO SAID LATCH MEANS TO CAUSE RELEASING MOVEMENT OF SAID LATCH MEANS UPON PREDETERMINED MOVEMENT OF SAID END OF SAID BIMETALLIC STRIP, (L) A RECIPROCABLY OPERABLE MANUAL OPERATING HANDLE MEMBER SUPPORTED IN SAID CASING AND MOVABLE BETWEEN FIRST AND SECOND ACTUATED POSITIONS, FOR MOVING SAID INSULATING SLIDE FROM SAID OPEN CIRCUIT TO SAID CLOSED CIRCUIT POSITION, AND (M) MEANS CARRIED BY SAID HANDLE AND ENGAGEABLE WITH SAID OTHER END OF SAID CONTACT CARRYING STRIP TO MOVE SAID CONTACT CARRYING STRIP LATERALLY AWAY FROM SAID SLIDE TO AN OPEN-CIRCUIT POSITION AS SAID HANDLE MOVES SAID SLIDE TO SAID LATCHED POSITION. 